Patent GB-798312-A (GB)
Title: Electronic digital computer
IPC: G06F7/498
Filed: 1955-11-02
Abstract: 798,312. Digital electric calculating apparatus. DEUTSCHE TELEPHONWERKE UND KABELINDUSTRIE AKT.-GES. Nov. 2, 1955 [Nov. 9, 1954], No. 31297/55. Class 106. In an electronic computer for addition, subtraction and multiplication, transfer of a number from an entry register to a totals register is effected by a train of pulses, equal in number to the radix being used, and fed in parallel to all orders of the entry register, these pulses serving to step the individual orders of the entry register through one cycle to their original reading, and, as an order reaches zero, being thereafter fed also to step the corresponding order of the totals, register. General. Each order E (units), Z (tens), H (hundreds), &c., of the entry register 7 comprises a decade counter tube 14 such as a Dekatron together with a two-state uni-stable double triode 13. The orders of the totals register 9, a single order digit register 8, a single order multiply register 4, and a counter 3, are similarly constituted. The keyboard 5 consists of ten digit keys 5A and further " add," " subtract " and " multiply " keys. Clock pulse generators 1, 2 deliver positive and negative pulses, respectively, but alternately. Addition. Assuming, for example, 42 is to be added to 39, digit keys 5A corresponding to the digits 4, 2 are operated in succession, then the " add " key, followed by the digit keys 3, 9, and again by the " add " key. Depression of the 4 digit key sets the counter tube 8R in the digit register 8 to the value 4, in known manner. On release of the key this value is automatically entered into the units order E of the entry register 7 as follows. A switch U1 is reversed as the digit key is depressed so that the next positive clock pulses closes a switch 17. As the digit key is released switch U1 reverts to the position shown so that the next positive clock pulse steps a distributer 6 to position one. The next clock pulse (negative) fed over the distributer arm 6a<SP>1</SP> closes a switch 18 and steps down the counter tube 14T (the entry register being zeroized) to the "- 1 " position, in which position the tube 14T pulses its associated double triode 13T which pulses the counter tube 14T to reset it to zero and switches to give a delayed positive pulse which closes a switch 19T and pulses contact 6II in the distributer to step the latter to position two, open the switch 18 and close a further switch in a delay member 20 so that the next clock pulse (positive) passes thereover to open all the switches 19 after a short delay. The next clock pulse (negative) over the distributer arm 6a<SP>1</SP> operates the hundreds order tubes 14H, 13H as indicated above for the tubes 14T, 13T, andin the subsequent successive positions of the distributer the same operations are repeated for the tens and units orders of the entry register. The next (negative) clock pulse is fed by the distributer to the digit register 8 where it steps down the tube 8R from value 4 to 3. The switch 18 being closed by this pulse, the next (positive) clock pulse is passed by the distributer arm 6a to the entry register units order E where it steps up the tube 14E to value 1. Subsequent negative pulses step down the tube 8R and the following positive pulses step up the tube 14E until the counter tube 8R goes from the " 0 " to " - 1 " position where the associated double triode 8FF functions (as described above for 13T) to advance the distributer to its zero position. The number 4 has now been transferred from the digit register 8 to the units order E of the entry register. Subsequent depression of the next digit key (value 2) sets up this value in the digit register 8, and, as the key is released a transfer operation as described above is initiated, the value 4 registered in the units order E of the entry register being first transferred to the tens order Z and the value 2 then being transferred to the units order E from the digit register. The number 42 is now stored in the entry register and upon subsequent depression of the " add " key is transferred to the totals register 9 as follows. Transfer from entry to totals register. A switch S5 is opened and switches S1, 21 are closed by the " add " key so that ten successive positive clock pulses are now fed over switch 21 to step the decade counter 3 simultaneously with all the order tubes 14 of the entry register ten steps, when the tube 3R pulses its doubletriode 3FF to open switch 21. When the respective counter tubes 14Z, 14E are switched on from the value 9 to the " invisible " value 10 their associated tubes 13Z, 13E are pulsed, switch their associated counter tubes to zero and close associated switches 19Z, 19E so that the subsequent positive pulses step the corresponding order tubes 15.5, 15.6 of the totals register synchronously with the tubes 14Z, 14E as they are stepped to the values 4, 2 respectively. All the operated switches 19 are also opened with switch 21, and at the same time all the counting tubes in the entry register are zeroized. The number 42 having now been transferred to the totals register 9 the " add " key is released to reset switches S1, S5. The digit keys 3, 9 are now operated to enter the value 39 into the entry register and then the " add " key is again operated to transfer this value from the entry into the totals register as described above where it is added to the previously entered value 42. Subtraction. The minuend is entered into the entry register 7 in the same manner as for addition and the " subtract " key is then depressed. This effects transfer of the minuend to the totals register 9, as for addition, reverses a switch U3 and opens switches N in the entry register, so that the entry register counter tubes 14 are not zeroized after the transfer but are set to 99, 999. As the " subtract " key is released switches U2, U2A are reversed, the switches N closed, and the digit keys 5A are reversed by a switch U5 so that on subsequently depressing one of the keys the digit register tube 8R is stepped to the nines complement of the selected value. The subtrahend value is thus entered into the entry register as its nines complement. The " subtract " key is now again depressed, when the value set up in the entry register is transferred to the totals register, as for addition except that the fugitive one is added to the lowest decade counter tube 15.6 by feeding the tens setting pulse from the double-triode tube 16.2 of the totals register over switch U2. Multiplication. The multiplicand is set into the entry register, as for addition, and the " multiply " key is then depressed. This reverses a switch U4, opens S2, S5, S7, closes S4, reverses the digit keys 5A so as to enter nines complements of subsequently selected values and shifts the totals register to the right by one order relative to a decade co-ordinator 10. Further contacts on the keyboard function to shift the totals register to the left by one order as each digit key is subsequently depressed. As the digit key corresponding to the first digit of the multiplier is depressed, the nines complement thereof is entered over switch U4 into the counter tube 4R of the multiply register 4 and the totals register 9 is shifted one step to the left. As the digit key is released, a switch S3 is temporarily closed to apply a single positive pulse to a switch 22 and to the double triode 3FF. Switch 22 closes, and the resultant undelayed pulse from tube 3FF over switch S4 advances the counter tube 4R one unit. The tube CFF switches, and feeds a delayed pulse over switch 22 to close switch 21 whereupon as above described for addition ten positive pulses are fed under control of the counter 3 to advance all orders of the entry register ten steps during which time the values registered therein are added to the associated orders of the totals register via the co-ordinator 10 except that at the end of the transfer the multiplicand remains in the entry register. The counter tube 4R is then advanced again over unit under control of the tube 3FF and a further transfer of the multiplier from the entry register to the totals register effected. In this way multiplication by the first digit of the multiplier is effected by repeated addition as the multiplier register 4 is advanced step by step. As this stage of the multiplication is completed the counter tube 4R is advanced to position " 10 " thereby pulsing tube 4FF which causes the counter tube 4R to be stepped to zero and opens switch 22. The next digit of the multiplier is now entered (by its nines complement) in the multiplier register 4, and the totals register moves one order to the left, so that when the selected digit key 5A is released, repeated addition of the multiplicand is effected as before described into the correct orders of the totals register, and so on for further digits of the multiplier. The order shift of the totals register may be effected in known manner electrically. Recording, Fig. 2. Printing wheels 37E, 37Z ... &c. may be set in accordance with the readings of the Dekatrons in the associated orders of the totals counter 9. The counter reading may, if desired, be added to or subtracted from an existing setting of the print wheels. For the counter setting to be added in, an " add " switch (not shown) is operated to reverse the switches R in the counter, and switch on a generator 30 which delivers ten slow counting pulses over line 31 followed by a transfer pulse over line 32. The ten slow pulses step all the orders of the totals counter ten steps and as each order reaches zero an associated relay AE, AZ, &c., is energized so that the corresponding printing wheel 37E, 37Z, &c., is then stepped by the subsequent pulses over line 31 with the counter order as it is advanced to its previous setting. As a printing wheel is stepped to zero a transfer contact KE is closed and transfer effected. by the transfer pulse. For negative entries a corresponding key i